Although medical x-ray tomography is now employed widely, and one of its most successful proponents, Littleton, has written "Size of the focal spot is extremely important. In every instance the focal spot should be the smallest obtainable", the use of microfocus x-ray tomography, or x-ray microtomography (XRMT), in medicine has been proposed to date only by the present applicants and one of their students. In nondestructive testing, NASA used XRMT successfully in the quality control of multi-layer printed circuit boards with an axial laminograph designed at IITRI by Moler. Absence of XRMT from medical literature probably can be explained by the fact that intense microfocus sources as small as 50 to 100 micra dia. suitable for medical use, and high quanta-absorption high-resolution solid state image intensifiers, have not been available. For two years the present applicants have worked with such a new medical microfocus source, developed by Tripp Research Corp., in various studies including XRMT imaging of tumors in breast tissue specimens from mastectomies. Correlation of gross and microscopic features of these tumors with their XRMT images has allowed visual and densitometric differentiation among tumor, adjacent fibrous tissue, and adipose tissue. These results encourage a broadening of scope with new objectives: 1) to include deep viscera, bone and middle ear for similar evaluation, at appropriate kv's for a. tumors and their extent of spread, and b. certain effects of trauma and inflammatory disease; 2) on the basis of these new results, assess clinical utility and patient dose of XRMT (dose should be smaller than conventional tomography); and 3) assuming success in 1) and 2), to develop design parameters for a prototype clinical multi-element XRMT with no moving parts. A matched source/intensifier system from TRC, scheduled for delivery to the Tulane labs in July, will implement these objectives. Period: One year.